South Korea's central bank on Tuesday warned against risks of household debt problems, saying that local households' debt-serving capacity worsened amid risks from low-credit borrowers and low-income families.

The Bank of Korea said in a semi-annual financial stability report that the growth of household debt slowed last year, but the capacity of households to repay debt deteriorated amid the protracted economic recovery.

The ratio of household debt against disposable income stood at a record 136 percent as of end-2012, up from 134 percent the previous year, according to the central bank.

Korea's household credit increased 5.2 percent on-year to a record 959 trillion won ($869.1 billion) last year, but households' income grew just 3.8 percent in the cited period.

"At a situation where households' financial soundness has not improved, it is becoming clearer that a pile-up in debt weighs on local households," the BOK said in the report.

The BOK described growing funding difficulty facing low-credit borrowers as "credit divide," saying that the growing number of such people relies on non-banking institutions or private money lenders as local banks are wary of extending loans to them.

Korean households' high indebtedness is the main bugbear for local policymakers as household debt problems are feared to curb consumer spending, sapping the economic growth.

The report said that 55.3 percent of borrowers with low creditworthiness tapped non-bank institutions excluding private money lenders as of end-2012 while only 15.2 percent used bank lending.

Credit loans extended by non-bank institutions to households amounted to 51.2 percent as of the end of last year, accounting for 33.3 percent of the total credit lending in the local financial sector, it added.

As for the corporate sector, the BOK said local shipbuilders, construction firms and shippers saw their financial health and profitability sharply worsen last year, raising default risks in those industries.

The prolonged economic slowdown and the sectoral business downturn led local shipbuilders and construction companies to see the ratio of operating profit against sales sharply decline last year, the BOK added. Shipping lines logged combined net losses for the second straight year in 2012 amid rising concerns over capital erosion.

The BOK also warned against a potential increase in cross-border capital flows due to potential ends of quantitative easing steps by major economies and economic uncertainty stemming from a weaker yen.

"If the yen's weakness accelerates, driven by Japan's aggressive monetary easing, there are risks that foreigners could pull their stock funds from the Seoul market as it will increase uncertainty for the Korean economy," the report said.

A weaker yen is feared to sap Seoul's exports as it hurts the price competitiveness of Korea's exporters when vying with Japanese rivals in overseas markets. The won has appreciated more than 20 percent against the yen since November. (Yonhap News)